salmonella enterica - pcrmax.com · invasine a gene (inva) salmonella enterica pcrmax ltd qpcr...

Invasine A gene (InvA)Salmonella entericaPCRmax Ltd qPCR testTM

150 tests

For general laboratory and research use only

1Quantification of Salmonella enterica genomes. Advanced kit handbook HB10.03.10

Published Date: 28/11/2017

Salmonella enterica is a motile, rod shaped, Gram-negative bacterium of theEnterobecteriacae family. There are over 2000 serovars that make up this species withgenomes ranging in length from 4.5-5 M nucleotides arranged in a circular configurationwith plasmids. These serovars can cause illnesses in human ranging from gastroenteritisto typhoid fever which kills around 500,000 people worldwide per year.

S. enterica can be found naturally on raw poultry and red meat and can contaminate somewater sources. When ingested from any of these sources, the bacterium secretes adhesionproteins called adhesins that mediate attachment to the host intestinal cells. Once withinthe host cells, the bacteria translocate to the liver and spleen where bacterial replicationcontinues. From the liver, bacteria are release back into the intestine and are subsequentlyexcreted. In areas with poor hygiene and water treatment, the bacteria can infect watersources at this time. A number of antibiotics have proven useful in reducing the length ofinfection.

The 3 main serovars cause widely different symptoms. Salmonella enterica serovar Typhicauses typhoid fever which initially presents with vomiting and diarrhea. This diseaseprogresses over several weeks leading to a high fever, abdominal pain and a rash on thechest or abdomen. Complications arise from intestinal hemorrhaging or perforation andinflammation of organs and bones.Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Enteritidis bothcause an infection with much milder symptoms than S. typhi, and are responsible forcausing salmonellosis, a type of gastroenteritits, with S. enteritidis being much morecommon than S. typhimurium. This disease is characterised by vomiting, diarrhea andabdominal pain but usually only last around 7 days before the immune system fights off theinfection. This is not the case in people with weak immune systems such as the elderly orinfants in whom the disease may become fatal if not treated.

Introduction to Salmonella enterica



MINMAX

The Salmonella enterica primers have been designed for the specific and exclusive invitro quantification of all Salmonella enteric subsp. enterica strains in which invasin A hasbeen described. The target sequence (invA) has previously been shown to be a goodgenetic marker for broad detection of pathogenic salmonella strains in other real timePCR based studies (Hadjinicolaou AV, et.al 2009). The primers and probe sequences inthis kit have 100% homology with a broad range of clinically relevant referencesequences based on a comprehensive bioinformatics analysis.

The PCR Max qPCR Kit for Salmonella enterica (S.enterica) genomes is designed for thein vitro quantification of S.enterica genomes. The kit is designed to have the broadestdetection profile possible whilst remaining specific to the S.enterica genome.

The primers and probe sequences in this kit have 100% homology with a broad range ofS.enterica sequences based on a comprehensive bioinformatics analysis.

If you require further information, or have a specific question about the detection profile ofthis kit then please send an e.mail to [email protected] and ourbioinformatics team will answer your question.

Specificity



Kit contents• S.enterica specific primer/probe mix (150 reactions BROWN)

FAM labelled

• S.enterica positive control template (for Standard curve RED)

• Internal extraction control primer/probe mix (150 reactions BROWN)VIC labelled as standard

• Internal extraction control DNA (150 reactions BLUE)

• Endogenous control primer/probe mix (150 reactions BROWN)FAM labelled

• RNase/DNase free water (WHITE)for resuspension of primer/probe mixes

• Template preparation buffer (YELLOW)for resuspension of and internal extraction control template, positive control template

and standard curve preparation

Reagents and equipment to be supplied by the userReal-time PCR Instrument

DNA extraction kitThis kit is designed to work well with all processes that yield high quality DNA with minimalPCR inhibitors.

Lyophilised 2X qPCR Master MixThis kit is designed to be compatible with all commercially available master mixes that runwith standard cycling conditions.

Pipettors and Tips

Vortex and centrifuge

Thin walled 1.5 ml PCR reaction tubes



Kit storage and stabilityThis kit is stable at room temperature but should be stored at -20ºC on arrival. Once thelyophilised components have been resuspended they should not be exposed totemperatures above -20ºC for longer than 30 minutes and unnecessary repeatedfreeze/thawing should be avoided. The kit is stable for six months from the date ofresuspension under these circumstances.If a standard curve dilution series is prepared this can be stored frozen for an extendedperiod. If you see any degradation in this serial dilution a fresh standard curve can beprepared from the positive control.PCRmax does not recommend using the kit after the expiry date stated on the pack.

Suitable sample materialAll kinds of sample material suited for PCR amplification can be used. Please ensure thesamples are suitable in terms of purity, concentration, and DNA integrity (An internal PCRcontrol is supplied to test for non specific PCR inhibitors). Always run at least one negativecontrol with the samples. To prepare a negative-control, replace the template DNA samplewith RNase/DNase free water.

Dynamic range of testUnder optimal PCR conditions PCRmax S.enterica detection kits have very high primingefficiencies of >95% and can detect less than 100 copies of target template.

Notices and disclaimersThis product is developed, designed and sold for research purposes only. It is not intended for human diagnostic or drugpurposes or to be administered to humans unless clearly expressed for that purpose by the Food and Drug Administration in theUSA or the appropriate regulatory authorities in the country of use. During the warranty period Master Mix detection kits allowprecise and reproducible data recovery combined with excellent sensitivity. For data obtained by violation to the general GLPguidelines and the manufacturer’s recommendations the right to claim under guarantee is expired. PCR is a proprietarytechnology covered by several US and foreign patents. These patents are owned by Roche Molecular Systems Inc. and havebeen sub-licensed by PE Corporation in certain fields. Depending on your specific application you may need a license fromRoche or PE to practice PCR. Additional information on purchasing licenses to practice the PCR process may be obtained bycontacting the Director of Licensing at Roche Molecular Systems, 1145 Atlantic Avenue, Alameda, CA 94501 or AppliedBiosystems business group of the Applera Corporation, 850 Lincoln Centre Drive, Foster City, CA 94404. In addition, the 5'nuclease assay and other homogeneous amplification methods used in connection with the PCR process may be covered by U.S. Patents 5,210,015 and 5,487,972, owned by Roche Molecular Systems, Inc, and by U.S. Patent 5,538,848, owned by ThePerkin-Elmer Corporation.

TrademarksMaster Mix™ is a trademark of Cole-Parmer Ltd.The PCR process is covered by US Patents 4,683,195, and 4,683,202 and foreign equivalents owned by Hoffmann-La RocheAG. BI, ABI PRISM® GeneAmp® and MicroAmp® are registered trademarks of the Applera Genomics (Applied BiosystemsCorporation). BIOMEK® is a registered trademark of Beckman Instruments, Inc.; iCycler™ is a registered trademark of Bio-RadLaboratories, Rotor-Gene is a trademark of Corbett Research. LightCycler™ is a registered trademark of the Idaho TechnologyInc. GeneAmp®, TaqMan® and AmpliTaqGold® are registered trademarks of Roche Molecular Systems, Inc., The purchase ofthe Master Mix reagents cannot be construed as an authorization or implicit license to practice PCR under any patents held byHoffmann-LaRoche Inc.



Principles of the testReal-time PCR

A S.enterica specific primer and probe mix is provided and this can be detected throughthe FAM channel.

The primer and probe mix provided exploits the so-called TaqMan® principle. During PCRamplification, forward and reverse primers hybridize to the S.enterica DNA. A fluorogenicprobe is included in the same reaction mixture which consists of a DNA probe labeled witha 5`-dye and a 3`-quencher. During PCR amplification, the probe is cleaved and thereporter dye and quencher are separated. The resulting increase in fluorescence can bedetected on a range of real-time PCR platforms.

Positive controlFor copy number determination and as a positive control for the PCR set up, the kitcontains a positive control template. This can be used to generate a standard curve of S.enterica copy number / Cq value. Alternatively the positive control can be used at a singledilution where full quantitative analysis of the samples is not required. Each time the kit isused, at least one positive control reaction must be included in the run. A positive resultindicates that the primers and probes for detecting the target S.enterica gene workedproperly in that particular experimental scenario. If a negative result is obtained the testresults are invalid and must be repeated. Care should be taken to ensure that the positivecontrol does not contaminate any other kit component which would lead to false-positiveresults. This can be achieved by handling this component in a Post PCR environment.Care should also be taken to avoid cross-contamination of other samples when adding thepositive control to the run. This can be avoided by sealing all other samples and negativecontrols before pipetting the positive control into the positive control well.

Negative controlTo validate any positive findings a negative control reaction should be included every timethe kit is used. For this reaction the RNase/DNase free water should be used instead oftemplate. A negative result indicates that the reagents have not become contaminatedwhile setting up the run.



Internal DNA extraction controlWhen performing DNA extraction, it is often advantageous to have an exogenous sourceof DNA template that is spiked into the lysis buffer. This control DNA is then co-purifiedwith the sample DNA and can be detected as a positive control for the extraction process.Successful co-purification and real-time PCR for the control DNA also indicates that PCRinhibitors are not present at a high concentration.

A separate primer and probe mix are supplied with this kit to detect the exogenous DNAusing real-time PCR. The primers are present at PCR limiting concentrations which allowsmultiplexing with the target sequence primers. Amplification of the control DNA does notinterfere with detection of the S.enterica target DNA even when present at low copynumber. The Internal control is detected through the VIC channel and gives a Cq value of28+/-3.

Endogenous controlTo confirm extraction of a valid biological template, a primer and probe mix is included todetect an endogenous gene. Detection of the endogenous control is through the FAMchannel and it is NOT therefore possible to perform a multiplex with the S.enterica primers.A poor endogenous control signal may indicate that the sample did not contain sufficientbiological material.



Component - resuspend in water Volume

S.enterica primer/probe mix (BROWN) 165 µlInternal extraction control primer/probe mix (BROWN)Endogenous control primer/probe mix (BROWN)

Pre-PCR pack

165 µl165 µl

Resuspension ProtocolTo minimize the risk of contamination with foreign DNA, we recommend that all pipettingbe performed in a PCR clean environment. Ideally this would be a designated PCR lab orPCR cabinet. Filter tips are recommended for all pipetting steps.

1. Pulse-spin each tube in a centrifuge before opening.This will ensure lyophilised primer and probe mix is in the base of the tube and is notspilt upon opening the tube.

2. Resuspend the primer/probe mixes in the RNase/DNase free water supplied,according to the table below:To ensure complete resuspension, vortex each tube thoroughly.

* This component contains high copy number template and is a VERY significant contamination risk. Itmust be opened and handled in a separate laboratory environment, away from the other components.

DNA extractionThe internal extraction control DNA can be added either to the DNA lysis/extraction bufferor to the DNA sample once it has been resuspended in lysis buffer.

DO NOT add the internal extraction control DNA directly to the unprocessed biologicalsample as this will lead to degradation and a loss in signal.

1. Add 4µl of the Internal extraction control DNA (BLUE) to each sample in DNAlysis/extraction buffer per sample.

2. Complete DNA extraction according to the manufacturers protocols.

3. Resuspend the internal control template and positive control template in thetemplate preparation buffer supplied, according to the table below:To ensure complete resuspension, vortex the tube thoroughly.

500 µlS.enterica Positive Control Template (RED) *

Component - resuspend in template preparation buffer Volume

Internal extraction control DNA (BLUE) 600 µlPre-PCR heat-sealed foil

Post-PCR heat-sealed foil



Component VolumeLyophilised 2X qPCR Master Mix

1 µlS.enterica primer/probe mix (BROWN)

Final Volume

1 µl

15 µl

10 µl

Internal extraction control primer/probe mix (BROWN)RNase/DNase free water (WHITE) 3 µl


1 µlEndogenous control primer/probe mix (BROWN)

Final Volume 15 µl

10 µl

RNase/DNase free water (WHITE) 4 µl

qPCR detection protocol1. For each DNA sample prepare a reaction mix according to the table below:

Include sufficient reactions for positive and negative controls.

2. For each DNA sample prepare an endogenous control reaction according to thetable below (Optional):This control reaction will provide crucial information regarding the quality of thebiological sample.

3. Pipette 15µl of each mix into individual wells according to your real-time PCRexperimental plate set up.

4. Prepare sample DNA templates for each of your samples.

5. Pipette 5µl of DNA template into each well, according to your experimental plateset up.For negative control wells use 5µl of RNase/DNase free water. The final volume ineach well is 20µl.

6. If a standard curve is included for quantitative analysis prepare a reaction mixaccording to the table below:


1 µlS.enterica primer/probe mix (BROWN)

Final Volume 15 µl

10 µl

RNase/DNase free water (WHITE) 4 µl



StepEnzyme activation

DenaturationDATA COLLECTION *

Time Temp

2 min10 s

60 s

95 oC95 oC

60 oCCycling x50

7. Preparation of standard curve dilution series.

1) Pipette 90µl of template preparation buffer into 5 tubes and label 2-62) Pipette 10µl of Positive Control Template (RED) into tube 23) Vortex thoroughly4) Change pipette tip and pipette 10µl from tube 2 into tube 35) Vortex thoroughly

Repeat steps 4 and 5 to complete the dilution series

8. Pipette 5µl of standard template into each well for the standard curve accordingto your experimental plate set up.The final volume in each well is 20µl.

qPCR amplification protocolAmplification conditions using Lyophilised 2X qPCR Master Mix.

* Fluorogenic data should be collected during this step through the FAM and VIC channels

International Units No international units

2 x 105 per µl2 x 104 per µl2 x 103 per µl2 x 102 per µl

20 per µl

2 per µl

Standard Curve Copy NumberTube 1 Positive control (RED)Tube 2Tube 3Tube 4Tube 5Tube 6



Interpretation of Resultsenviro commensalNO

+ / - + > 35

+ / - + ≤ 35 EXPERIMENT FAILEDdue to test contamination

*

+ + - NEGATIVE RESULT

- + - SAMPLE PREPARATION FAILED

+ / - - + / - EXPERIMENT FAILED

POSITIVE QUALITATIVE RESULTdo not report copy number as this

may be due to poor sample extraction- -+

-+ + POSITIVE QUANTITATIVE RESULTcalculate copy number

+ / - - POSITIVE QUANTITATIVE RESULTcalculate copy number+

InterpretationPositivecontrol

Negativecontrol

Internalcontrol(VIC)

+ / -

≤ 30

Target(FAM)

> 30

+ / -

> 30

-

-+ / -

*Where the test sample is positive and the negative control is positive with a Cq > 35, thesample must be reinterpreted based on the relative signal strength of the two results:

Positive control template (RED) is expected to amplify between Cq 16 and 23. Failure tosatisfy this quality control criterion is a strong indication that the experiment has beencompromised.

If the sample amplifies < 5 Cq earlier thanthe negative control then the positivesample result is invalidated and the resultshould be determined inconclusive due totest contamination. The test for thissample should be repeated.

Sample Negative control

∆Cq<5

INCONCLUSIVE

If the sample amplifies > 5 Cq earlier thanthe negative control then the sampleshould be reinterpreted (via the tableabove) with the negative control verifiedas negative.

Sample Negative control

∆Cq>5

SAMPLEPOSITIVE



Internal PCR controlThe Cq value obtained with the internal control will vary significantly depending on theextraction efficiency, the quantity of DNA added to the PCR reaction and the individualmachine settings. Cq values of 28±3 are within the normal range. When amplifying a S.enterica sample with a high genome copy number, the internal extraction control may notproduce an amplification plot. This does not invalidate the test and should be interpretedas a positive experimental result.

Endogenous controlThe signal obtained from the endogenous control primer and probe set will vary accordingto the amount of biological material present in a given sample. An early signal indicatesthe presence of a good yield of biological material. A late signal suggests that littlebiological material is present in the sample.



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